<!DOCTYPE html>
<style>
div {
  height: 240px;
}
#f {
  height: 0;
  overflow: hidden;
  padding: 0;
  border: none;
}
</style>
There should be a visible fieldset below:
<div>
  <fieldset id="f">This is fieldset</fieldset>
</div>
<script>
h = document.body.clientHeight;
f.style.height = "auto";
</script>

